A Right Circular Cone: A 3-dimensional solid in which the base is a circle. The side of a cone is formed by straight lines which connect the circular base to a vertex. The height is the perpendicular distance from the vertex to the base and meets the base in the center of the circle.

Remember that this is only true because we are assuming that the triangular sides are congruent; that is, we are working with a regular pyramid. Note that in a regular pyramid it is also true that (1) each triangle makes the same angle with the base and (2) the height connects the vertex to the center of the regular polygonal base.

Despite the fact that well over 1,000,000 stone blocks weighing between 2 and 150 tons were manually installed, the exact measurements of the sides of the base and the angles of the triangles forming the sides are off by less than 0.1% from that of a perfectly regular pyramid.